PLEASE WRITE in with your
questions, since that is the only
way we can keep this column
format going. When referring to
already published Q/As (for
follow-ups), provide the number as
a reference.
Notice that references to
addresses and Web sites are now
placed in a group, separate from
the text, at the end of this column
under “Sources.”
Q358: “I still enjoy the sound and
operation of two-stroke glow
fueled model aircraft engines. I’ve
used many of these engines over
the years with excellent success.
I’ve read several books on the
subject, but now feel I need
something more than just the
basics. Is there anything new out
there (besides electric power)?”
A358: In the early 1990s, long-time model-engine expert and AMA
Hall of Famer Dave Gierke wrote an excellent book titled 2-Stroke
Glow Engines for R/C Aircraft: Volume 1. It has been one of the
fueled-engine flier’s standard references for many years.
Now a retired schoolteacher, Dave is devoting much more time
to being a model-aircraft author. His latest book is exactly what you
requested. It is Power: Beyond the Basics: 2-Stroke Glow Engines
Vol. 2. The book is full color, published in an 81/2 x 11-inch format,
and contains 143 pages of super-detailed current engine data and
references.
The many
chapters include
such subjects as
throttle design
and development,
how carburetors
work,
understanding
fuel-delivery
systems, future
fuel-injection
possibilities, fuel components, and choosing the right type of fuel
for your engine.
Air Age Media publishes this book. It is available through
RCStore.com, from the AMA, and directly from Dave. The list
price is $24.95.
I may be into electric power for the most part, but this book
provides some incredible information about two-stroke glow
engines.
Q359: “I have a new electric powered ducted fan scale aircraft and
want to be able to catapult launch it with the help of a bungee or
elastic cord. Can you provide some of the details, like type of cord,
length, attachment to the models, tension, etc.?”
A359: I’ve seen noted model author Jim Ryan of Cincinnati, Ohio,
launch his various ducted-fan aircraft at the NEAT [Northeast
Electric Aircraft Technology] Fair every year. I asked him your
questions, and he replied:
“My bungee setup is pretty simple. I use a 20-foot length of a
rubber tubing called ‘Thera-Band’ that can be purchased at Total
Home Comforts. You want the blue color that denotes ‘extra heavy
duty.’ A 25 feet spool will cost you $33.95.
“This elastic cord (bungee as we call it) is
attached to a tent stake at one end and at the
other end to 20-feet of glider towline. This
towline isn’t really critical; any lightweight
nylon cord (fishing line) should be fine. I
take care about the links because that’s
where breaks occur. I use a 1-inch diameter
welded steel ring (from The Home Depot)
between the stake and the bungee.
“On the other end (aircraft end) I took a
short piece of dowel and drilled a hole down
the center for the towline. The towline is
then threaded through and knotted. I worked
down inside the rubber tubing and then tied a
ligature around the end. By doing this there
are no strain points, so a break is very
unlikely.
“Finally I have a smaller 3/4-inch diameter
welded steel ring at the end of the towline
and this gets hooked to the model. Standard
towline hooks can be used on your model
with the exact location resulting after a few
trial launches.
“I’ve never fooled around with
launching ramps, but some guys really like
them. There are lots of resources on this
subject on RCGroups and modelers who
have done this in various ways. You should
try a search on that forum.
“As far as the amount of tension placed
on the bungee cord, the really scientific
guys use a fish scale to measure the pull.
I’ve heard that the rule of thumb is like 5
times the weight of the model.
“I tend to do it by feel: as you pull back
on the bungee the tension will build
steadily. Then there comes a point where
tension increases rapidly. You’re now close
to the elastic limit of the cord, and this is
the point to stop, and take one step forward
from that point.
“I like this approach better than using a
scale; the bungee only has so much to give,
and if that’s not enough, you need to double
the bungee or use heavier cord. Just be very
careful when doing all of this, because a
bungee cord that gets loose can be outright
dangerous.”
Q360: “I build mostly micro/indoor models,
which in many cases may only weigh a few
grams. I’ve been concerned that my small
capacity digital scale might be out of
calibration. Are there any sources for known
weights that can check on the scale
calibration?”
A360: This reader is lucky, because I
received an interesting tip from another
reader that will help answer this question.
The latter informed me that all standard
mint coins of the same denomination have
close to the same weight. A typical penny
weighs 2.500 grams, a nickel is 5.000
grams, a dime is 2.268 grams, and a quarter
is 5.670 grams.
As shown, a nickel on my 120-gram
maximum-capacity digital scale weighed
exactly 5.0 grams. That means it is close
enough. I don’t believe these scales provide
for adjustments, but using these coin
standards should enable you to come up
with a calibration conversion chart. This
will allow you to zero in on exact weights.
Q361: “I’m trying to design my own
biplane and was wondering how you
calculate the center of gravity when two
wings are involved?”
A361: Just to make sure, I asked my flying
partner, Tom Hunt. Among many things, he
is an aerodynamics expert.
He was kind enough to provide a
descriptive diagram, which I have included
in this column, that explains exactly how
the biplane CG can be calculated. Thank
you, Tom!
Q362: “I noticed that all RC servo
manufacturers state the output torque for each unit. This torque figure is expressed
usually in Ounce/Inches (Oz./In.). Knowing
that this amount of power (torque) is
available how do I relate it to the model
speed, control surface size and the amount of
deflection?”
A362: I did a considerable search on the
Internet and came up with an excellent Web
site that is identified as “Electric Flight in
Colorado.” I was unable to get the name of
the person who is responsible for this
wonderful site, but his E-mail address is on
the home page if you want to thank him for
this effort.
The first thing I found on this Web site
was a Servo Torque Calculator. You enter
your model’s estimated maximum speed,
control-surface width and length, and
maximum deflection. Then the calculator
gives you the required servo torque.
That by itself would prove to be
interesting to many. But I went deeper into
this site and found other interesting items,
such as a “Wing Loading” calculator, “Glow
to Electric Conversion” calculator, and an
“Electric Motor” calculator. This information
is freely available to anyone who visits the
site.
I’ve only begun to play with some of these
features and found it to be totally fascinating.
Please at least give it a try.
106 MODEL AVIATION
Q363: “I’ve always been fascinated with
the operation of various engines,
especially those used for model power
applications. Is there any way I can learn
about the operation of these engines in a
simple format—not too technical?”
A363: Reader Joe Mielnicki referred me
to a Web site that Matt Keveney created.
It is an amazing find. Matt wrote:
“I have loved mechanical things since
I was a kid. Engines in particular have
always intrigued me. All my life I’ve
pored over books, studying cutaway
drawings, hungry to understand how
things work. These pages are an attempt
to share that magic.”
As you work through Matt’s site, you
can find animated drawings that show the
operation of engines such as four-strokes,
two-strokes, Wankels, Gnome rotarys,
and jet propulsion, CO2 motors, and many
more. You owe it to yourself to go to this
site and look through it in detail. You
won’t be disappointed. MA
Sources:
Air Age Media
(203) 431-9000
https://secure.rcstore.com
AMA store
(800) 435-9262
www.modelaircraft.org/shopama
Dave Gierke
1276 Ransom Rd.
Lancaster NY 14086
Total Home Comforts
(888) 358-0298
www.totalhomecomforts.com/tubing.htm
Electric Flight in Colorado
www.csd.net/~cgadd/eflight/calcs_servo.h
tm
Matt Keveney
www.keveney.com/Engines.html
Edition: Model Aviation - 2008/08
Page Numbers: 103,104,106
Edition: Model Aviation - 2008/08
Page Numbers: 103,104,106
PLEASE WRITE in with your
questions, since that is the only
way we can keep this column
format going. When referring to
already published Q/As (for
follow-ups), provide the number as
a reference.
Notice that references to
addresses and Web sites are now
placed in a group, separate from
the text, at the end of this column
under “Sources.”
Q358: “I still enjoy the sound and
operation of two-stroke glow
fueled model aircraft engines. I’ve
used many of these engines over
the years with excellent success.
I’ve read several books on the
subject, but now feel I need
something more than just the
basics. Is there anything new out
there (besides electric power)?”
A358: In the early 1990s, long-time model-engine expert and AMA
Hall of Famer Dave Gierke wrote an excellent book titled 2-Stroke
Glow Engines for R/C Aircraft: Volume 1. It has been one of the
fueled-engine flier’s standard references for many years.
Now a retired schoolteacher, Dave is devoting much more time
to being a model-aircraft author. His latest book is exactly what you
requested. It is Power: Beyond the Basics: 2-Stroke Glow Engines
Vol. 2. The book is full color, published in an 81/2 x 11-inch format,
and contains 143 pages of super-detailed current engine data and
references.
The many
chapters include
such subjects as
throttle design
and development,
how carburetors
work,
understanding
fuel-delivery
systems, future
fuel-injection
possibilities, fuel components, and choosing the right type of fuel
for your engine.
Air Age Media publishes this book. It is available through
RCStore.com, from the AMA, and directly from Dave. The list
price is $24.95.
I may be into electric power for the most part, but this book
provides some incredible information about two-stroke glow
engines.
Q359: “I have a new electric powered ducted fan scale aircraft and
want to be able to catapult launch it with the help of a bungee or
elastic cord. Can you provide some of the details, like type of cord,
length, attachment to the models, tension, etc.?”
A359: I’ve seen noted model author Jim Ryan of Cincinnati, Ohio,
launch his various ducted-fan aircraft at the NEAT [Northeast
Electric Aircraft Technology] Fair every year. I asked him your
questions, and he replied:
“My bungee setup is pretty simple. I use a 20-foot length of a
rubber tubing called ‘Thera-Band’ that can be purchased at Total
Home Comforts. You want the blue color that denotes ‘extra heavy
duty.’ A 25 feet spool will cost you $33.95.
“This elastic cord (bungee as we call it) is
attached to a tent stake at one end and at the
other end to 20-feet of glider towline. This
towline isn’t really critical; any lightweight
nylon cord (fishing line) should be fine. I
take care about the links because that’s
where breaks occur. I use a 1-inch diameter
welded steel ring (from The Home Depot)
between the stake and the bungee.
“On the other end (aircraft end) I took a
short piece of dowel and drilled a hole down
the center for the towline. The towline is
then threaded through and knotted. I worked
down inside the rubber tubing and then tied a
ligature around the end. By doing this there
are no strain points, so a break is very
unlikely.
“Finally I have a smaller 3/4-inch diameter
welded steel ring at the end of the towline
and this gets hooked to the model. Standard
towline hooks can be used on your model
with the exact location resulting after a few
trial launches.
“I’ve never fooled around with
launching ramps, but some guys really like
them. There are lots of resources on this
subject on RCGroups and modelers who
have done this in various ways. You should
try a search on that forum.
“As far as the amount of tension placed
on the bungee cord, the really scientific
guys use a fish scale to measure the pull.
I’ve heard that the rule of thumb is like 5
times the weight of the model.
“I tend to do it by feel: as you pull back
on the bungee the tension will build
steadily. Then there comes a point where
tension increases rapidly. You’re now close
to the elastic limit of the cord, and this is
the point to stop, and take one step forward
from that point.
“I like this approach better than using a
scale; the bungee only has so much to give,
and if that’s not enough, you need to double
the bungee or use heavier cord. Just be very
careful when doing all of this, because a
bungee cord that gets loose can be outright
dangerous.”
Q360: “I build mostly micro/indoor models,
which in many cases may only weigh a few
grams. I’ve been concerned that my small
capacity digital scale might be out of
calibration. Are there any sources for known
weights that can check on the scale
calibration?”
A360: This reader is lucky, because I
received an interesting tip from another
reader that will help answer this question.
The latter informed me that all standard
mint coins of the same denomination have
close to the same weight. A typical penny
weighs 2.500 grams, a nickel is 5.000
grams, a dime is 2.268 grams, and a quarter
is 5.670 grams.
As shown, a nickel on my 120-gram
maximum-capacity digital scale weighed
exactly 5.0 grams. That means it is close
enough. I don’t believe these scales provide
for adjustments, but using these coin
standards should enable you to come up
with a calibration conversion chart. This
will allow you to zero in on exact weights.
Q361: “I’m trying to design my own
biplane and was wondering how you
calculate the center of gravity when two
wings are involved?”
A361: Just to make sure, I asked my flying
partner, Tom Hunt. Among many things, he
is an aerodynamics expert.
He was kind enough to provide a
descriptive diagram, which I have included
in this column, that explains exactly how
the biplane CG can be calculated. Thank
you, Tom!
Q362: “I noticed that all RC servo
manufacturers state the output torque for each unit. This torque figure is expressed
usually in Ounce/Inches (Oz./In.). Knowing
that this amount of power (torque) is
available how do I relate it to the model
speed, control surface size and the amount of
deflection?”
A362: I did a considerable search on the
Internet and came up with an excellent Web
site that is identified as “Electric Flight in
Colorado.” I was unable to get the name of
the person who is responsible for this
wonderful site, but his E-mail address is on
the home page if you want to thank him for
this effort.
The first thing I found on this Web site
was a Servo Torque Calculator. You enter
your model’s estimated maximum speed,
control-surface width and length, and
maximum deflection. Then the calculator
gives you the required servo torque.
That by itself would prove to be
interesting to many. But I went deeper into
this site and found other interesting items,
such as a “Wing Loading” calculator, “Glow
to Electric Conversion” calculator, and an
“Electric Motor” calculator. This information
is freely available to anyone who visits the
site.
I’ve only begun to play with some of these
features and found it to be totally fascinating.
Please at least give it a try.
106 MODEL AVIATION
Q363: “I’ve always been fascinated with
the operation of various engines,
especially those used for model power
applications. Is there any way I can learn
about the operation of these engines in a
simple format—not too technical?”
A363: Reader Joe Mielnicki referred me
to a Web site that Matt Keveney created.
It is an amazing find. Matt wrote:
“I have loved mechanical things since
I was a kid. Engines in particular have
always intrigued me. All my life I’ve
pored over books, studying cutaway
drawings, hungry to understand how
things work. These pages are an attempt
to share that magic.”
As you work through Matt’s site, you
can find animated drawings that show the
operation of engines such as four-strokes,
two-strokes, Wankels, Gnome rotarys,
and jet propulsion, CO2 motors, and many
more. You owe it to yourself to go to this
site and look through it in detail. You
won’t be disappointed. MA
Sources:
Air Age Media
(203) 431-9000
https://secure.rcstore.com
AMA store
(800) 435-9262
www.modelaircraft.org/shopama
Dave Gierke
1276 Ransom Rd.
Lancaster NY 14086
Total Home Comforts
(888) 358-0298
www.totalhomecomforts.com/tubing.htm
Electric Flight in Colorado
www.csd.net/~cgadd/eflight/calcs_servo.h
tm
Matt Keveney
www.keveney.com/Engines.html
Edition: Model Aviation - 2008/08
Page Numbers: 103,104,106
PLEASE WRITE in with your
questions, since that is the only
way we can keep this column
format going. When referring to
already published Q/As (for
follow-ups), provide the number as
a reference.
Notice that references to
addresses and Web sites are now
placed in a group, separate from
the text, at the end of this column
under “Sources.”
Q358: “I still enjoy the sound and
operation of two-stroke glow
fueled model aircraft engines. I’ve
used many of these engines over
the years with excellent success.
I’ve read several books on the
subject, but now feel I need
something more than just the
basics. Is there anything new out
there (besides electric power)?”
A358: In the early 1990s, long-time model-engine expert and AMA
Hall of Famer Dave Gierke wrote an excellent book titled 2-Stroke
Glow Engines for R/C Aircraft: Volume 1. It has been one of the
fueled-engine flier’s standard references for many years.
Now a retired schoolteacher, Dave is devoting much more time
to being a model-aircraft author. His latest book is exactly what you
requested. It is Power: Beyond the Basics: 2-Stroke Glow Engines
Vol. 2. The book is full color, published in an 81/2 x 11-inch format,
and contains 143 pages of super-detailed current engine data and
references.
The many
chapters include
such subjects as
throttle design
and development,
how carburetors
work,
understanding
fuel-delivery
systems, future
fuel-injection
possibilities, fuel components, and choosing the right type of fuel
for your engine.
Air Age Media publishes this book. It is available through
RCStore.com, from the AMA, and directly from Dave. The list
price is $24.95.
I may be into electric power for the most part, but this book
provides some incredible information about two-stroke glow
engines.
Q359: “I have a new electric powered ducted fan scale aircraft and
want to be able to catapult launch it with the help of a bungee or
elastic cord. Can you provide some of the details, like type of cord,
length, attachment to the models, tension, etc.?”
A359: I’ve seen noted model author Jim Ryan of Cincinnati, Ohio,
launch his various ducted-fan aircraft at the NEAT [Northeast
Electric Aircraft Technology] Fair every year. I asked him your
questions, and he replied:
“My bungee setup is pretty simple. I use a 20-foot length of a
rubber tubing called ‘Thera-Band’ that can be purchased at Total
Home Comforts. You want the blue color that denotes ‘extra heavy
duty.’ A 25 feet spool will cost you $33.95.
“This elastic cord (bungee as we call it) is
attached to a tent stake at one end and at the
other end to 20-feet of glider towline. This
towline isn’t really critical; any lightweight
nylon cord (fishing line) should be fine. I
take care about the links because that’s
where breaks occur. I use a 1-inch diameter
welded steel ring (from The Home Depot)
between the stake and the bungee.
“On the other end (aircraft end) I took a
short piece of dowel and drilled a hole down
the center for the towline. The towline is
then threaded through and knotted. I worked
down inside the rubber tubing and then tied a
ligature around the end. By doing this there
are no strain points, so a break is very
unlikely.
“Finally I have a smaller 3/4-inch diameter
welded steel ring at the end of the towline
and this gets hooked to the model. Standard
towline hooks can be used on your model
with the exact location resulting after a few
trial launches.
“I’ve never fooled around with
launching ramps, but some guys really like
them. There are lots of resources on this
subject on RCGroups and modelers who
have done this in various ways. You should
try a search on that forum.
“As far as the amount of tension placed
on the bungee cord, the really scientific
guys use a fish scale to measure the pull.
I’ve heard that the rule of thumb is like 5
times the weight of the model.
“I tend to do it by feel: as you pull back
on the bungee the tension will build
steadily. Then there comes a point where
tension increases rapidly. You’re now close
to the elastic limit of the cord, and this is
the point to stop, and take one step forward
from that point.
“I like this approach better than using a
scale; the bungee only has so much to give,
and if that’s not enough, you need to double
the bungee or use heavier cord. Just be very
careful when doing all of this, because a
bungee cord that gets loose can be outright
dangerous.”
Q360: “I build mostly micro/indoor models,
which in many cases may only weigh a few
grams. I’ve been concerned that my small
capacity digital scale might be out of
calibration. Are there any sources for known
weights that can check on the scale
calibration?”
A360: This reader is lucky, because I
received an interesting tip from another
reader that will help answer this question.
The latter informed me that all standard
mint coins of the same denomination have
close to the same weight. A typical penny
weighs 2.500 grams, a nickel is 5.000
grams, a dime is 2.268 grams, and a quarter
is 5.670 grams.
As shown, a nickel on my 120-gram
maximum-capacity digital scale weighed
exactly 5.0 grams. That means it is close
enough. I don’t believe these scales provide
for adjustments, but using these coin
standards should enable you to come up
with a calibration conversion chart. This
will allow you to zero in on exact weights.
Q361: “I’m trying to design my own
biplane and was wondering how you
calculate the center of gravity when two
wings are involved?”
A361: Just to make sure, I asked my flying
partner, Tom Hunt. Among many things, he
is an aerodynamics expert.
He was kind enough to provide a
descriptive diagram, which I have included
in this column, that explains exactly how
the biplane CG can be calculated. Thank
you, Tom!
Q362: “I noticed that all RC servo
manufacturers state the output torque for each unit. This torque figure is expressed
usually in Ounce/Inches (Oz./In.). Knowing
that this amount of power (torque) is
available how do I relate it to the model
speed, control surface size and the amount of
deflection?”
A362: I did a considerable search on the
Internet and came up with an excellent Web
site that is identified as “Electric Flight in
Colorado.” I was unable to get the name of
the person who is responsible for this
wonderful site, but his E-mail address is on
the home page if you want to thank him for
this effort.
The first thing I found on this Web site
was a Servo Torque Calculator. You enter
your model’s estimated maximum speed,
control-surface width and length, and
maximum deflection. Then the calculator
gives you the required servo torque.
That by itself would prove to be
interesting to many. But I went deeper into
this site and found other interesting items,
such as a “Wing Loading” calculator, “Glow
to Electric Conversion” calculator, and an
“Electric Motor” calculator. This information
is freely available to anyone who visits the
site.
I’ve only begun to play with some of these
features and found it to be totally fascinating.
Please at least give it a try.
106 MODEL AVIATION
Q363: “I’ve always been fascinated with
the operation of various engines,
especially those used for model power
applications. Is there any way I can learn
about the operation of these engines in a
simple format—not too technical?”
A363: Reader Joe Mielnicki referred me
to a Web site that Matt Keveney created.
It is an amazing find. Matt wrote:
“I have loved mechanical things since
I was a kid. Engines in particular have
always intrigued me. All my life I’ve
pored over books, studying cutaway
drawings, hungry to understand how
things work. These pages are an attempt
to share that magic.”
As you work through Matt’s site, you
can find animated drawings that show the
operation of engines such as four-strokes,
two-strokes, Wankels, Gnome rotarys,
and jet propulsion, CO2 motors, and many
more. You owe it to yourself to go to this
site and look through it in detail. You
won’t be disappointed. MA
Sources:
Air Age Media
(203) 431-9000
https://secure.rcstore.com
AMA store
(800) 435-9262
www.modelaircraft.org/shopama
Dave Gierke
1276 Ransom Rd.
Lancaster NY 14086
Total Home Comforts
(888) 358-0298
www.totalhomecomforts.com/tubing.htm
Electric Flight in Colorado
www.csd.net/~cgadd/eflight/calcs_servo.h
tm
Matt Keveney
www.keveney.com/Engines.html
